8 Plate Tectonics 8.1 What Is Plate Tectonics? CHAPTER 8 Plate Tectonics EXIT CHAPTER 8.1 What Is Plate Tectonics? 8.2 Types of Plate Boundaries 8.3 Causes of Plate Movement 8.4 Plate Movements and Continental Growth CHAPTER OUTLINE

8.1 What is Plate Tectonics? CHAPTER 8 Plate Tectonics CHAPTER HOME 8.1 What is Plate Tectonics? VOCABULARY Alfred Wegner proposed the hypothesis of continental drift to explain how a single land mass had separated into separate continents, which drifted apart. plate tectonics continental drift mid-ocean ridge Fossil evidence found in South America and Africa support the hypothesis that the continents were once joined. South America Africa Areas in which mesosaurus fossils have been found SECTION OUTLINE

8.1 What is Plate Tectonics? CHAPTER 8 Plate Tectonics CHAPTER HOME 8.1 What is Plate Tectonics? VOCABULARY Alfred Wegner proposed the hypothesis of continental drift to explain how a single land mass had separated into separate continents, which drifted apart. plate tectonics continental drift mid-ocean ridge Later discoveries supported the idea that the continents had been connected, but demonstrated that the continents were not “drifting” but attached to moving lithospheric, or tectonic, plates. SECTION OUTLINE

8.1 What is Plate Tectonics? CHAPTER 8 Plate Tectonics CHAPTER HOME 8.1 What is Plate Tectonics? VOCABULARY The theory of plate tectonics explains the occurrence of volcanoes and earthquakes in concentrated belts along plate boundaries. plate tectonics continental drift mid-ocean ridge Earthquakes Volcanoes SECTION OUTLINE

8.1 What is Plate Tectonics? CHAPTER 8 Plate Tectonics CHAPTER HOME 8.1 What is Plate Tectonics? VOCABULARY Plate tectonics also account for a distinctive pattern in the age and magnetism of rocks that spread out from mid-ocean ridges on the ocean floor. plate tectonics continental drift mid-ocean ridge Mid-Atlantic Ridge, Atlantic Ocean East Pacific Rise, Pacific Ocean SECTION OUTLINE

8 Plate Tectonics plate tectonics CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY plate tectonics continental drift plate tectonics mid-ocean ridge The theory that the lithosphere is made of plates that move and interact with each other at their boundaries. SECTION OUTLINE

8 Plate Tectonics continental drift CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY plate tectonics continental drift continental drift mid-ocean ridge A hypothesis that Earth’s continents move on Earth’s surface. SECTION OUTLINE

8 Plate Tectonics mid-ocean ridge CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY plate tectonics continental drift mid-ocean ridge mid-ocean ridge A long chain of mountains with a central rift valley that is located along a divergent boundary on the ocean floor. SECTION OUTLINE

8.2 Types of Plate Boundaries CHAPTER 8 Plate Tectonics CHAPTER HOME 8.2 Types of Plate Boundaries VOCABULARY Plates move apart at divergent boundaries. A rift valley is an example of a divergent boundary on land. divergent boundary rift valley rift convergent boundary subduction boundary Type of Boundary Characteristic Features Current Examples Process Involved Divergent sea-floor spreading Mid-Atlantic Ridge East Pacific Rise mid-ocean ridges rift valleys earthquake activity at fracture zones along mid-ocean ridges volcanic activity deep-sea trench collision boundary transform boundary SECTION OUTLINE

8.2 Types of Plate Boundaries CHAPTER 8 Plate Tectonics CHAPTER HOME 8.2 Types of Plate Boundaries VOCABULARY Plates move toward each other at convergent boundaries. One plate may subduct under the other, as happens at deep-sea trenches, or the two plates may collide. divergent boundary rift valley rift convergent boundary subduction boundary Type of Boundary Characteristic Features Current Examples Process Involved ocean-ocean subduction islands of Indonesia Mariana Islands deep-sea trenches volcanic island arcs earthquake activity Convergent deep-sea trench collision boundary transform boundary SECTION OUTLINE

8.2 Types of Plate Boundaries CHAPTER 8 Plate Tectonics CHAPTER HOME 8.2 Types of Plate Boundaries VOCABULARY Plates move toward each other at convergent boundaries. One plate may subduct under the other, as happens at deep-sea trenches, or the two plates may collide. divergent boundary rift valley rift convergent boundary subduction boundary Type of Boundary Characteristic Features Current Examples Process Involved Convergent deep-sea trench collision boundary ocean-continent subduction western coast of South America deep-sea trench bordering continent volcanoes along coast of continent earthquake activity transform boundary SECTION OUTLINE

8.2 Types of Plate Boundaries CHAPTER 8 Plate Tectonics CHAPTER HOME 8.2 Types of Plate Boundaries VOCABULARY Plates move toward each other at convergent boundaries. One plate may subduct under the other, as happens at deep-sea trenches, or the two plates may collide. divergent boundary rift valley rift convergent boundary subduction boundary Type of Boundary Characteristic Features Current Examples Process Involved Convergent deep-sea trench collision boundary continent-continent collision Himalayas high continental mountain chains earthquake activity transform boundary SECTION OUTLINE

8.2 Types of Plate Boundaries CHAPTER 8 Plate Tectonics CHAPTER HOME 8.2 Types of Plate Boundaries VOCABULARY Plates move past each other at transform boundaries. divergent boundary rift valley rift convergent boundary subduction boundary Type of Boundary Characteristic Features Current Examples Process Involved plates sliding past each other San Andreas Fault North Anatolian Fault (Turkey) fracture zones along mid-ocean ridges earthquake activity Transform deep-sea trench collision boundary transform boundary SECTION OUTLINE

8 Plate Tectonics divergent boundary CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY divergent boundary rift valley divergent boundary rift A boundary between two lithospheric plates that are moving apart. convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

8 Plate Tectonics rift valley CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY divergent boundary rift valley rift valley rift A deep valley at a point where lithospheric plates are moving apart, such as at a mid-ocean ridge. convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

8 Plate Tectonics rift A crack or opening in Earth’s crust. CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY divergent boundary rift valley rift rift A crack or opening in Earth’s crust. convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

8 Plate Tectonics convergent boundary CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY divergent boundary rift valley convergent boundary rift A boundary between two plates that are moving toward each other, or converging. convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

8 Plate Tectonics subduction boundary CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY divergent boundary rift valley subduction boundary rift A convergent boundary where an oceanic plate is plunging beneath another, overriding plate. convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

8 Plate Tectonics deep-sea trench CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY divergent boundary rift valley deep-sea trench rift A long, narrow, steep-sided trough that runs parallel to continental margins or to volcanic island chains. convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

8 Plate Tectonics collision boundary CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY divergent boundary rift valley collision boundary rift A convergent boundary where two continents have come together and are welded into a single, larger continent. convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

8 Plate Tectonics transform boundary CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY divergent boundary rift valley transform boundary rift A boundary between two plates that are sliding past each other. convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

8.3 Causes of Plate Movement CHAPTER 8 Plate Tectonics CHAPTER HOME 8.3 Causes of Plate Movement VOCABULARY and slab pull are hypothetical models for the causes of plate movements. Mantle convection, ridge push, mantle convection ridge push slab pull Mantle convection This image shows one model of how mantle convection may contribute to plate movement. Mid-ocean ridge Deep-sea trench This image shows as section of the East Pacific Rise, a mid-ocean ridge. SECTION OUTLINE

8 Plate Tectonics mantle convection CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY mantle convection ridge push mantle convection slab pull A process by which heat from Earth’s inner and outer cores is transferred through the mantle. SECTION OUTLINE

8 Plate Tectonics ridge push CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY mantle convection ridge push ridge push slab pull A force that is exerted by cooling, subsiding rock on the spreading lithospheric plates at a mid-ocean ridge. SECTION OUTLINE

8 Plate Tectonics slab pull CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY mantle convection ridge push slab pull slab pull A force at a subduction boundary that the sinking edge of the subducting plate exerts on the rest of the plate. SECTION OUTLINE

8.4 Plate Movements and Continental Growth CHAPTER 8 Plate Tectonics CHAPTER HOME 8.4 Plate Movements and Continental Growth VOCABULARY Pangaea craton Plate movements have caused the positions of Earth’s landmasses to shift over time. Scientists think that all continents were once part of a single landmass they call Pangaea. terrane Pangaea 200 million years ago Pathalassa Ocean Tethys Sea SECTION OUTLINE

8.4 Plate Movements and Continental Growth CHAPTER 8 Plate Tectonics CHAPTER HOME 8.4 Plate Movements and Continental Growth VOCABULARY Pangaea craton Plate movements have caused the positions of Earth’s landmasses to shift over time. Scientists think that all continents were once part of a single landmass they call Pangaea. terrane 180 million years ago Laurasia Gondwana SECTION OUTLINE

8.4 Plate Movements and Continental Growth CHAPTER 8 Plate Tectonics CHAPTER HOME 8.4 Plate Movements and Continental Growth VOCABULARY Pangaea craton Plate movements have caused the positions of Earth’s landmasses to shift over time. Scientists think that all continents were once part of a single landmass they call Pangaea. terrane 65 million years ago North America South America Africa India Asia Australia Antarctica SECTION OUTLINE

8.4 Plate Movements and Continental Growth CHAPTER 8 Plate Tectonics CHAPTER HOME 8.4 Plate Movements and Continental Growth VOCABULARY Pangaea craton Plate movements have caused the positions of Earth’s landmasses to shift over time. Scientists think that all continents were once part of a single landmass they call Pangaea. terrane Modern Day North America South America Africa Europe Asia Australia Antarctica SECTION OUTLINE

8.4 Plate Movements and Continental Growth CHAPTER 8 Plate Tectonics CHAPTER HOME 8.4 Plate Movements and Continental Growth VOCABULARY Pangaea craton Plate movements have caused the positions of Earth’s landmasses to shift over time. Scientists think that all continents were once part of a single landmass they call Pangaea. terrane Scientists use fossils, the ages of rocks, and other geologic evidence to reconstruct past land movement. SECTION OUTLINE

8.4 Plate Movements and Continental Growth CHAPTER 8 Plate Tectonics CHAPTER HOME 8.4 Plate Movements and Continental Growth VOCABULARY Pangaea craton The shapes of the landmasses have also changed. At the core of each continent is a craton, the oldest rock on the continent. terrane The North American craton Canadian Shield Platform SECTION OUTLINE

8.4 Plate Movements and Continental Growth CHAPTER 8 Plate Tectonics CHAPTER HOME 8.4 Plate Movements and Continental Growth VOCABULARY Pangaea craton The shapes of the landmasses have also changed. At the core of each continent is a craton, the oldest rock on the continent. terrane Processes associated with plate tectonics add new materials to a continent over time. For example, terranes are blocks of lithospheric plates that contribute to continental growth. SECTION OUTLINE

8 Plate Tectonics Pangaea CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY Pangaea craton Pangaea terrane The name of a hypothetical landmass consisting of all the continents welded together, which evidence indicates existed about 250 million years ago. SECTION OUTLINE

8 Plate Tectonics craton CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY Pangaea craton craton terrane The ancient core of a continent, which is tectonically stable. SECTION OUTLINE

8 Plate Tectonics terrane CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY Pangaea craton terrane terrane A large block of lithospheric plate that has been moved, often over a distance of thousands of kilometers, and attached to the edge of a continent. SECTION OUTLINE

I. What is Plate Tectonics? CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY I. What is Plate Tectonics? plate tectonics A. Early Ideas about Plate Movements continental drift B. The Theory of Plate Tectonics mid-ocean ridge 1. Locations of Earthquakes and Volcanoes 2. Magnetism and the Age of the Ocean Floor KEY IDEA SUMMARY

II. Types of Plate Boundaries? CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY II. Types of Plate Boundaries? divergent boundary A. Divergent Boundaries rift valley B. Convergent Boundaries rift 1. Subduction Boundaries convergent boundary 2. Collision Boundaries subduction boundary C. Transform Boundaries deep-sea trench collision boundary transform boundary KEY IDEA SUMMARY

III. Causes of Plate Movement CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY III. Causes of Plate Movement mantle convection A. Mantle Convection ridge push B. Ridge Push slab pull C. Slab Pull KEY IDEA SUMMARY

IV. Plate Movement and Continental Growth CHAPTER 8 Plate Tectonics CHAPTER HOME VOCABULARY IV. Plate Movement and Continental Growth Pangaea A. Reconstructing the Past craton B. Plate Tectonics and Pangaea terrane 1. Formation of Pangaea 2. Breakup of Pangaea C. Plate Tectonics and Continental Growth D. Sources of Growth Material 1. Deep-Sea Sediments 2. Igneous Rock 3. River Sediments 4. Terranes KEY IDEA SUMMARY

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